09-04-2011, 12:05 PM
[attachment=11915]
RF BASED SPY ROBOT
Introduction:
Robotics is a fascinating subject- more so, if you have to fabricate a robot yourself. The field of robotics encompasses a number of engineering disciplines such as electronics (including electrical), structural, pneumatics and mechanical.
The structural part involves use of frames, beams, linkages, axles, etc. the mechanical parts/ accessories comprise various types of gears (spurs, crowns, bevels, worms and differential gear systems), pulleys and belts, drive systems(differentials, castors, wheels and steering) etc. The pneumatics plays a vital role in generating specific pushing and pulling movements such as those simulating arms or leg movement. Pneumatic grippers are also used with advantage in robotics because of their simplicity and cost effectiveness. The electrical items include DC and Stepper motors, actuators, electrical grips, clutches and their control. The electronic parts involves remote control, sensors (touch sensors, light sensor, collision sensor, etc), there interface circuitry and a microcontroller for overall control functions.
CHAPTER -2
CIRCUIT DISCRIPTION AND WORKING
Project Overview:
What we present here is an elementary robotic land rover that can be control remotely using primarily the RF mode. The RF remote control has the advantage of adequate range (up to 200m with proper antenna) besides being omni directional. On the other hand, an IR remote would function over a limited range of about 5m and the remote transmitter has to be oriented towards the receiver module quite precisely. However, the cost involve in using RF modules is much higher than that of IR components and as such, we have included the replacement alternative of RF modules with their IR counterparts for using the IR remote control.
The proposed land rover can move in forward and reverse direction. You will also be able to steer it towards left and right directions. While being turn to left and right, the corresponding blinking LEDs would blink to indicate the direction of its turning. Similarly, during reverse movement, reversing LEDs would be lit. Front and rear bumpers are provided using long operating lever of micro switches to switch off the drive motors during any collision. The decoder being used for the project has latch outputs and as such you don’t have to keep the buttons on remote control pressed for more than a few milliseconds. This helps prolong the battery life for remote.
The entire project is split up into sections and each section is explain in the sufficient detail to enable you not only to fabricate the present design but also exploit this principles for evolving your own design with added functions.
Forward and reverse movement:
To keep your design as simple as possible, we have coupled a 30rpm geared 6v DC motor to the left front wheel and another identical motor to the right front wheel. Both these front motors are mounted side by side by facing in opposite direction. Wheel rims (5cm diameter) along with rubber wheels are directly coupled to each of the motor shafts. This arrangement does not require separate axles.
During forward (or reverse) movement of the vehicle, the two wheel shafts, as viewed from the motor ends, would move in opposite directions (one clockwise and the other anticlockwise). For reversing the direction, you simply have to reverse the DC supply polarity of the two motors driving the respective wheels.
Steering control:
There are different methods available for steering a robotic vehicle. The commonly used ones are:
1. Front wheels are used for steering, while rear wheels are used for driving eg. Tractors.
2. Front wheels are used for steering as well as driving eg, in most light vehicles. In these vehicles (such as cars), the front wheels are coupled using a differential gear arrangement. It comes into play only when one wheel needs to rotate differentially with respect to their axes.
Drive circuit for the motors:
Here is a typical circuit for driving one of the motors, in forward or reverse direction, coupled to, say the left hand front wheel. Simultaneously, the right direction for the moving the vehicle in the same direction. It means that input terminals of the motor drive circuit for the right hand motor have to be fed with reverse polarity control signals compared to those of the left hand motor drive circuit.
In the H-bridge motor drive circuit when A1 input is made high and A2 is made low, transistor T1(NPN) is forward biased and driven into saturation, while transistor T2 (PnP), being reverse biased, is cut off. This extends the battery’s positive rail to terminal1 of the motor. Simultaneously with input A2 at ground potential, transistor T3 (NPN) is cutoff, while T4 (PnP) is forward biased and driven into saturation. This results in ground being extended to terminal2 of the motor. Thus the motor rotates in one direction.
Now, if the two inputs are logically complemented, the motor will run in the opposite direction. When both the inputs are at the same logic level (gnd or vcc), the motor is at rest. Thus WI can control the movement (forward, reverse and stop) as well as the direction of rotation of the motor with the help of logic level of the two control input signals to the motor.
RF BASED SPY ROBOT
Introduction:
Robotics is a fascinating subject- more so, if you have to fabricate a robot yourself. The field of robotics encompasses a number of engineering disciplines such as electronics (including electrical), structural, pneumatics and mechanical.
The structural part involves use of frames, beams, linkages, axles, etc. the mechanical parts/ accessories comprise various types of gears (spurs, crowns, bevels, worms and differential gear systems), pulleys and belts, drive systems(differentials, castors, wheels and steering) etc. The pneumatics plays a vital role in generating specific pushing and pulling movements such as those simulating arms or leg movement. Pneumatic grippers are also used with advantage in robotics because of their simplicity and cost effectiveness. The electrical items include DC and Stepper motors, actuators, electrical grips, clutches and their control. The electronic parts involves remote control, sensors (touch sensors, light sensor, collision sensor, etc), there interface circuitry and a microcontroller for overall control functions.
CHAPTER -2
CIRCUIT DISCRIPTION AND WORKING
Project Overview:
What we present here is an elementary robotic land rover that can be control remotely using primarily the RF mode. The RF remote control has the advantage of adequate range (up to 200m with proper antenna) besides being omni directional. On the other hand, an IR remote would function over a limited range of about 5m and the remote transmitter has to be oriented towards the receiver module quite precisely. However, the cost involve in using RF modules is much higher than that of IR components and as such, we have included the replacement alternative of RF modules with their IR counterparts for using the IR remote control.
The proposed land rover can move in forward and reverse direction. You will also be able to steer it towards left and right directions. While being turn to left and right, the corresponding blinking LEDs would blink to indicate the direction of its turning. Similarly, during reverse movement, reversing LEDs would be lit. Front and rear bumpers are provided using long operating lever of micro switches to switch off the drive motors during any collision. The decoder being used for the project has latch outputs and as such you don’t have to keep the buttons on remote control pressed for more than a few milliseconds. This helps prolong the battery life for remote.
The entire project is split up into sections and each section is explain in the sufficient detail to enable you not only to fabricate the present design but also exploit this principles for evolving your own design with added functions.
Forward and reverse movement:
To keep your design as simple as possible, we have coupled a 30rpm geared 6v DC motor to the left front wheel and another identical motor to the right front wheel. Both these front motors are mounted side by side by facing in opposite direction. Wheel rims (5cm diameter) along with rubber wheels are directly coupled to each of the motor shafts. This arrangement does not require separate axles.
During forward (or reverse) movement of the vehicle, the two wheel shafts, as viewed from the motor ends, would move in opposite directions (one clockwise and the other anticlockwise). For reversing the direction, you simply have to reverse the DC supply polarity of the two motors driving the respective wheels.
Steering control:
There are different methods available for steering a robotic vehicle. The commonly used ones are:
1. Front wheels are used for steering, while rear wheels are used for driving eg. Tractors.
2. Front wheels are used for steering as well as driving eg, in most light vehicles. In these vehicles (such as cars), the front wheels are coupled using a differential gear arrangement. It comes into play only when one wheel needs to rotate differentially with respect to their axes.
Drive circuit for the motors:
Here is a typical circuit for driving one of the motors, in forward or reverse direction, coupled to, say the left hand front wheel. Simultaneously, the right direction for the moving the vehicle in the same direction. It means that input terminals of the motor drive circuit for the right hand motor have to be fed with reverse polarity control signals compared to those of the left hand motor drive circuit.
In the H-bridge motor drive circuit when A1 input is made high and A2 is made low, transistor T1(NPN) is forward biased and driven into saturation, while transistor T2 (PnP), being reverse biased, is cut off. This extends the battery’s positive rail to terminal1 of the motor. Simultaneously with input A2 at ground potential, transistor T3 (NPN) is cutoff, while T4 (PnP) is forward biased and driven into saturation. This results in ground being extended to terminal2 of the motor. Thus the motor rotates in one direction.
Now, if the two inputs are logically complemented, the motor will run in the opposite direction. When both the inputs are at the same logic level (gnd or vcc), the motor is at rest. Thus WI can control the movement (forward, reverse and stop) as well as the direction of rotation of the motor with the help of logic level of the two control input signals to the motor.
